Bamboo cane from which reeds for the double reed family of woodwind instruments are made grows in the form of a hollow tube. Making a double reed involves selecting cane of an appropriate diameter, cutting a segment of an appropriate length, and splitting it lengthwise—either in thirds or in quarters, depending on the preference of a reed-maker. Double reeds are made from these split pieces of cane, which pieces of cane include an outer surface which is referred to herein as a “bark side” and an inner surface which is referred to herein as a “gouged side.”
Bamboo cane has a cross-section formed of two concentric circular arcs and, as split, is too thick for reed making. As such, gouging is one of the first processes carried out on the split piece of cane. Gouging reduces the wall thickness of the piece of cane, and creates a crescent-like cross-section whose thickness is greatest in the centre of the cross-section and becomes thinner at each edge.
Prior art gouging machines traditionally have included: (a) a cane bed with a trough of circular cross-section whose radius of curvature matches that of the bark side of the cane to be gouged; and (b) a cutting tool which is able to slide on a guide rod, which guide rod is fixed parallel to the trough. In the gouging process, a split piece of cane is placed bark side down in the trough of the cane bed to support the cane during the gouging process. The gouging process consists of planing excess material from the gouged side of the split piece of cane using a blade with a curved cutting edge until the cross-section of the cane has reached desired dimensions. The desired dimensions are determined partly by the curvature of the blade, and partly by adjusting mechanisms that regulate: (a) the minimum gap between the trough of the cane bed and the cutting tool; and (b) the lateral position of the cutting tool above the trough. In one type of gouging process, known as single radius gouging, the blade is centered over the trough and the curvature of the blade is directly imparted to the gouged side of the cane. In another type of gouging process, known as double radius gouging, the blade is positioned off center, over the trough, and a symmetrical gouge cross-section is created by repeatedly turning the split piece of cane, end for end, as the gouging process progresses.
Before undergoing the gouging process, the split cane may undergo one or more preparatory operations which save time and wear on the gouging machine itself. These processes may include the following steps: (a) a top cut which reduces the cross-section of the split cane to a desired overall height and width; and (b) a pre-gouge which reduces the wall thickness of the split cane by removing excess material from the gouged side. These preparatory operations are carried out by tools of simple design which rapidly reduce the cross-section of the piece of split cane to slightly above its finished dimensions.
The successful production of double reeds depends in part upon being able to gouge cane to consistent dimensions within specifications, which dimensions include the centre thickness, as measured at all points along the length of the cane, and the side thickness, as measured at a given distance from the centre. It is because of this that problems have arisen with traditional gouging machines. Cane is a naturally growing plant, and does not grow in perfectly round or straight tubes. As such, its outside diameter does not consistently match the circular cross-section of a gouging machine trough. Thus, in spite of the best efforts of reed makers in selecting and splitting tubes of cane, there is a persistent tendency for the curvature of the bark side of a split piece of cane to fail to conform to the curvature of the gouging machine trough along at least a part of its length. In particular, if the curvature of the cane is smaller than that of the trough, the edges of the cane fail to contact the trough and will be gouged too thin—resulting in sides which are too thin in relation to centre thickness. However, if the curvature of the cane is larger than that of the trough, the centre of the cane fails to contact the trough and will be gouged too thin—resulting in a centre thickness which is too thin in relation to side thickness.
Another problem with traditional gouging machines relates to achieving consistent centering of the center of the gouged cross-section between the sides of the split piece of cane. In a traditional gouging machine, the split piece of cane is centered in the trough of the cane bed by eye, and the gouging process tends to cause it to shift position in the trough. As a result, variation in centering the center of the gouged cross-section frequently occurs. Finally, adjusting mechanisms of traditional gouging machines have not made it possible to make adjustments of precisely controlled and known amounts, thereby making it necessary to use trial and error methods when making changes to the dimensions of gouged cane.
In light of the above, there is a need to improve the quality of reeds for the double reed family of woodwind instruments by improving the reliability and accuracy of one of the processes involved in producing such reeds, which process is traditionally called the gouging process.